Vein filter

ABSTRACT

A vessel filter comprising a first region and a second region wherein the filter is movable between a collapsed position for delivery to the vessel and an expanded position for placement within the vessel. A first region has a filter portion having a converging region to direct particles toward the center of the filter and the second region is flared in the expanded position to have a transverse dimension increasing toward a second end portion opposite the first end portion. The second region includes a vessel engaging portion at the second end portion. The first region includes a plurality of spaced apart elongated struts with adjacent struts being joined and a spacer extending radially with respect to a longitudinal axis of the filter.

This application is a continuation of application Ser. No. 11/888,929,filed Aug. 3, 2007, now U.S. Pat. No. 8,062,326 which claims priorityfrom provisional application Ser. No. 60/840,888, filed Aug. 29, 2006,and is a continuation-in part of application Ser. No. 10/889,429, filedJul. 12, 2004, now U.S. Pat. No. 7,704,266 which claims priority fromprovisional application Ser. No. 60/572,274, filed May 18, 2004, and isa continuation-in-part of application Ser. No. 10/805,796 filed Mar. 22,2004, now U.S. Pat. No. 7,338,512 which claims priority from provisionalapplication Ser. No. 60/538,379, filed Jan. 22, 2004. The entirecontents of each of these applications are incorporated herein byreference.

BACKGROUND

1. Technical Field

This application relates to a vascular filter and more particularly to avein filter for capturing blood clots within the vessel.

2. Background of Related Art

Passage of blood clots to the lungs is known as pulmonary embolism.These clots typically originate in the veins of the lower limbs and canmigrate through the vascular system to the lungs where they can obstructblood flow and therefore interfere with oxygenation of the blood.Pulmonary embolisms can also cause shock and even death.

In some instances, blood thinning medication, e.g. anticoagulants suchas Heparin, or sodium warfarin can be given to the patient. Thesemedications, however, have limited use since they may not be able to beadministered to patients after surgery or stroke or given to patientswith high risk of internal bleeding. Also, this medication approach isnot always effective in preventing recurring blood clots.

Therefore, surgical methods to reduce the likelihood of such pulmonaryembolisms by actually blocking the blood clot from reaching the lungshave been developed. To this end, minimally invasive surgical techniqueshave been developed involving the placement of a mechanical barrier inthe inferior vena cava. These barriers are in the form of filters andare typically inserted through either the femoral vein in the patient'sleg or the right jugular vein in the patient's neck or arm under localanesthesia. The filters are then advanced intravascularly to theinferior vena cava where they are expanded to block migration of theblood clots from the lower portion of the body to the heart and lungs.

These prior filters take various forms. One type of filter is composedof coiled wires such as disclosed in U.S. Pat. Nos. 5,893,869 and6,059,825. Another type of filter consists of legs with free ends havinganchors for embedding in the vessel wall to hold the filter. Thesefilters are disclosed, for example, in U.S. Pat. Nos. 4,688,553,4,781,173, 4,832,055, and 5,059,205, 5,984,947 and 6,007,558. Anothertype of filter is disclosed in U.S. Pat. No. 6,214,025 consisting ofwires twisted together to form a cylindrical anchoring portionconforming to the inner vessel wall surface to exert a radial force anda conical filtering portion.

Several factors have to be considered in designing vein filters. Onefactor is that the filter needs to be securely anchored within thevessel wall, while avoiding traumatic engagement and damage to the wallas well as damage to the neighboring abdominal aorta. Another factor isthat the filter must be collapsible to a sufficiently small size to beeasily maneuvered and atraumatically advanced intravascularly to theinferior vena cava or other target vessel. Thirdly, the filter shoulddirect the blood clots to the center of the vessel to improvedissolution of the clot within the vessel by the blood flow.

The filters disclosed in the commonly assigned co-pending applicationSer. No. 10/889,429 (hereinafter “the '429 application”), the entirecontents of which are incorporated herein by reference, satisfy theforegoing parameters. The filters have sufficient anchoring force toretain the filter within the vessel while providing atraumatic contactwith the vessel wall, have a minimized insertion (collapsed) profile tofacilitate delivery through the vascular system to the surgical site,and direct migration of the captured blood clots to the center of thevessel. The filters also provide simplified insertion through thefemoral or the right jugular vein or arm into the inferior vena cava.

The filters of the '429 application can advantageously be readilyremoved minimally invasively, e.g. intravascularly, from the patient,thus advantageously providing for a temporary filter. Thus, thesefilters advantageously strike the balance of having structure to providesufficient anchoring while enabling atraumatic removal from the vesselafter a period of time. Certain filters of the '429 application alsoadvantageously have a retrieval end configured to facilitate grasping bya snare as well as to facilitate withdrawal by providing a smoothtransition into a retrieval sheath.

The filters of the '429 are very effective in achieving their desiredfunctions, whether used as a permanent or temporary filter. The presentapplication provides a modification to the filters to even furtherfacilitate removal if used as a temporary filter.

The filters of the '429 application also have effective retention hooksto grasp the vessel wall to prevent migration of the filter. The presentapplication provides an alternative retention hook to even furtherenhance retention.

SUMMARY

The present invention provides modifications to the filters of the '429application. The invention provides a vessel filter comprising a firstregion and a second region. The filter is movable between a collapsedposition for delivery to the vessel and an expanded position forplacement within the vessel. The first region has a filter portionhaving a converging region to direct particles toward the center of thefilter and includes a plurality of spaced apart elongated struts and aplurality of connecting struts extending at an angle from the elongatedstruts. The second region is flared in the expanded position to have atransverse dimension increasing toward a second end portion opposite thefilter portion and includes a vessel engaging portion at the second endportion. The first region has a spacer extending radially with respectto a longitudinal axis of the filter.

In a preferred embodiment, the spacer is formed from a spiral cutout inthe first region of the filter. In one embodiment, the spacer comprisestwo portions extending on opposite sides of the filter. The spacer ispreferably formed integrally with the filter and forms one or moreloops. In some embodiments, two spacers are provided. In a preferredembodiment, the filter is formed from a laser cut tube composed of shapememory material.

In a preferred embodiment, the converging region terminates in a tubularportion, each of the elongated struts in the first region extendoutwardly from the tubular portion, and the at least one spacer extendsradially from the tubular portion and is formed from a spiral cut intothe tubular portion. The spacer preferably has a looped shape memoryposition and during delivery has a collapsed position substantiallyaligned with the tubular portion.

In one embodiment the vessel engaging hooks of the filter include a heelextending past the hook. The vessel engaging hooks can also have aplurality of teeth.

The present invention also provides a vessel filter comprising a bodymade from a single tube cut to create a plurality of elongated struts, atubular region proximal of the struts and a spiral cut in the tubularregion to form a radially extending spacer. The spacer in the collapsedposition is substantially flush with the tubular portion and in theexpanded position extends outwardly from the tubular portion to space aretrieval region of the filter from the vessel wall.

In one embodiment the filter includes interconnecting struts in afiltering region of the body to form closed geometric shapes.

In a preferred embodiment, the retrieval region includes a hook having acutout exposing an internal annular surface and vessel engaging hooksare positioned at the second region.

In one embodiment, the spiral cut has a first cut portion to form afirst spacer and a second cut portion to form a second spacer. In oneembodiment, the first and second spacers extend from a proximal end ofthe respective first and second cut portions and in another embodimentthe first and second spacers extend from a distal end of the respectivefirst and second cut portions. In another embodiment, the first spacerextends from a proximal end of the first cut portion and the secondspacer extends from the distal end of the second cut portion.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiment(s) of the present disclosure are described hereinwith reference to the drawings wherein:

FIG. 1 is a perspective view of a first embodiment of the vein filter ofthe present invention in the collapsed (retracted) configuration, andshown removed from a delivery tube/sheath;

FIG. 2 is an enlarged broken side view of a portion of the vein filterof FIG. 1;

FIG. 3 is a developed view of the retention hooks of the vein filter ofFIG. 1;

FIG. 4A is a perspective view of the vein filter of FIG. 1 in anexpanded (radially extending) configuration;

FIG. 4B is a side view of the vein filter of FIG. 4A;

FIG. 5 is a front view of the vein filter of FIG. 4A;

FIG. 6 is a side view of the vein filter of FIG. 1 with the struts inthe expanded configuration and the spacers in the collapsedconfiguration;

FIG. 7 is a close up perspective view of the detail of FIG. 6;

FIG. 8 is a perspective view of a cranial end of a filter of the '429application showing the retrieval hook of the filter;

FIG. 9 is a view similar to FIG. 8 except showing the cranial end of thefilter of FIG. 1, the spacers shown in the collapsed position;

FIG. 9A is a perspective view of an alternate embodiment of theretrieval portion of the filter having an extended hook;

FIG. 10 is a view similar to FIG. 9, except showing a broken view of thespacers extending radially from the tubular portion;

FIG. 11 is a perspective view of an alternate embodiment of the veinfilter of the present invention having a single spacer loop, the filterand spacer shown in the expanded configuration;

FIG. 12 is a front view of the filter of FIG. 11;

FIGS. 13, 14, and 15 illustrate delivery and placement of the vesselfilter of FIG. 1 in the inferior vena cava wherein FIG. 13 illustratesinitial insertion of the delivery sheath through the femoral vein, FIG.14 illustrates the delivery sheath being advanced toward the inferiorvena cava just below (upstream) the juncture of the renal arteries; andFIG. 15 illustrates the filter in the expanded placement configurationin the inferior vena cava;

FIG. 15A illustrates an initial step in removal of the filter from theinferior vena cava by a retrieval snare and catheter;

FIG. 16 is a side view of an alternate embodiment of the filter of thepresent invention having spacers at different angles to the longitudinalaxis of the filter, the spacers shown in the expanded position;

FIG. 17 is a perspective view of an alternate embodiment of the filterof the present invention having a single spacer extending in a singleplane, the spacers shown in the expanded position;

FIG. 17A is a close up view of the area of detail of FIG. 17;

FIG. 18 is a perspective view of another alternate embodiment of thefilter of the present invention having a single spacer extending inmultiple planes;

FIG. 19 is a perspective view of the cranial end of another alternateembodiment of the filter of the present invention have two spacers, thespacers shown in the expanded position;

FIG. 19A is a view similar to FIG. 19 except showing the spacers in thecollapsed position;

FIG. 20 is a perspective view of the cranial end of yet anotheralternate embodiment of the filter of the present invention having twospacers, the spacers shown in the expanded position;

FIG. 20A is a view similar to FIG. 20 except showing the spacers in thecollapsed position;

FIG. 21 is a perspective view of the cranial end of another alternateembodiment of the filter of the present invention showing the twospacers in the expanded position;

FIGS. 22A-22C illustrate another alternate embodiment of the cranial endof the filter of the present invention wherein FIG. 22A is a perspectiveview of the cranial end in the collapsed configuration, FIG. 22B is aside view in the collapsed configuration and FIG. 22C is a perspectiveview in the expanded configuration.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Turning now to the drawings, wherein like reference numerals identifysimilar or like components throughout the several views, the veinfilters of the present invention are described for placement within theinferior vena cava to capture blood clots or other particles which couldotherwise pass to the lungs.

The filter is movable from a low profile collapsed configuration tofacilitate insertion through the delivery sheath to a larger expandedplacement configuration to enable atraumatic engagement with the vesselwalls to secure (mount) the filter within the inferior vena cava. Thefilter is preferably substantially bell-shaped and preferably has aflared or mounting region (portion/section) and a filtering region(portion/section). The filtering region has inwardly directed struts,terminating in a converging region, thereby directing particles towardthe central axis of the filter. By directing the particles to thecenter, they will be exposed to greater blood flow (since there isgreater flow at the center than near the wall of the vessel) whichimproves dissolution of the particles. The filter increases intransverse dimension to form a flared region. The flare provides lesscontact area than a straight region, resulting in less tissue ingrowthto facilitate removal of the filter if desired. The flare also reducesthe chance of vessel distortion if inserted into a curved vena cava. Thefilter also has spacers to space the cranial end of the filter from thevessel wall to facilitate removal.

Turning now to details of the filter of the present invention and withinitial reference to FIGS. 1 and 2, the filter is designated generallyby reference numeral 10 and is shown in a collapsed configuration fordelivery. Filter 10 is preferably formed from a single tube 11. In apreferred embodiment, the filter tube 11 is composed of shape memorymaterial, such as Nitinol, a nickel titanium alloy, or elgiloy, however,other materials such as stainless steel are also contemplated. Aplurality of cutouts are formed in the filter 10, preferably by lasercutting although other techniques are contemplated. In the illustratedembodiment, six elongated cutouts are formed, creating six strips orstruts 14 of substantially uniform width separated by the cutouts.

The collapsed configuration of filter 10 reduces the overall profile tofacilitate delivery to the site. The diameter or transverse dimension offilter 10 in the collapsed configuration is preferably about 2 mm andmore preferably about 1.7 mm. Other dimensions are also contemplated.The filter is thus preferably dimensioned for insertion through a 6French delivery system and through a 6 French catheter. The diameter ortransverse dimensions of the filter in the expanded placementconfigurations (e.g. FIGS. 4A and 4B) is greater than the diameter ortransverse dimension in the collapsed (delivery) configuration of FIG.1.

FIGS. 4-5 illustrate the expanded placement configuration of the filter10. FIGS. 6 and 7 illustrate the expanded configuration of the strutswith the spacers in the collapsed position (not exposed from the sheath)to help illustrate the invention, a configuration that would occurbriefly. Filter 10 is generally bell-shaped in configuration. Filter 10has a flared region 17 and a converging region 21 at the filteringsection 19. The transverse dimension of the filter at the flared (ormounting/anchoring) region 17 is greater than the transverse dimensionat filtering section 19. Diameters (or transverse dimensions) preferablyrange from about 18 mm to about 32 mm, depending on the internaldiameter of the vessel wall as will be explained in more detail below.Other dimensions are also contemplated. The elongated struts 14 arespaced apart as shown and extend at an angle away from the longitudinalaxis L of filter 10 in region 17 to provide a flare. Preferably, thisangle or taper is about 8°, although other dimensions are contemplated.When expanded, the six struts 14, as shown, are preferably spacedapproximately 60 degrees apart. It is also contemplated that a fewer orgreater number of struts and spacing other than 60 degrees be provided.

Filtering section 19 extends from the flared region 17, and extendstoward the central longitudinal axis L of the filter 10 and convergesinto tubular portion 18 at the cranial end of the filter.

The struts 14 of filter 10 terminate in hooks 72 a, 72 b which extendsubstantially perpendicular from the strut, achieved by torquing thestruts at the region 85 so the hooks bend out of the plane. A first setof hooks 72 a is larger than a second set of hooks 72 b. Preferably whenformed in a laser cut tube, hooks 72 a are formed so that they occupy aregion equivalent to the transverse dimension of two adjacent struts.Smaller hooks 72 b are spaced axially with respect to each other andaxially inwardly with respect to larger hooks 72 a as in the filterhooks of the '429 application to minimize the collapsed profile(transverse dimension) of the filter when collapsed for insertion. Thepenetrating tips 76 a, 76 b of hooks 72 a, 72 b, respectively, penetratethe tissue to retain the filter, preferably temporarily, and pointdistally, toward the cranial (or distal) end of the filter.

Each of the hooks 72 a, 72 b has a series of teeth 79 a, 79 b,respectively to engage the vessel wall to provide additional retentionto prevent movement of the filter in the caudal direction. In apreferred embodiment, the larger hooks 72 a have four teeth and thesmaller hooks 72 b have three teeth, although a different number ofteeth could be provided. A heel 77 a, 77 b, is provided which extendspast (proximally or caudal of) the respective hook 72 a, 72 b tofunction as a stop to prevent the filter strut portions from goingthrough the vessel wall. The angle of the heel 77 b in the smaller hooks72 b is less than the angle in the larger hooks 72 a to provide room fornesting of the hooks as shown in FIG. 3. For clarity, not all of thehooks are fully labeled. Note this hook configuration with the teethand/or heel can be utilized with the filters of the '429 application.

The six filter struts or strut portions 14 curve outwardly from tubularportion 18, extend radially therefrom and divide into two connectingfilter struts or strut portions 14 a, 14 b (preferably of equal width,although differing dimensions are contemplated) that angle way from eachother (in different directions) to extend to the connecting strutportion of an adjacent strut 14. Thus, connecting strut portion 14 a ofone strut 14 interconnects with the connecting strut portion 14 b of anadjacent strut at joining region 14 d. This forms closed geometricshapes 25, preferably substantially diamond shaped in configuration. Forclarity, not all of the identical parts are labeled in the drawing.

In the illustrated embodiment, preferably six struts are providedforming twelve interconnecting struts, however a different number ofstruts and closed geometric shapes can be provided. Note that althoughall six struts 14 are shown interconnected, it is also contemplated thatfewer than all the struts can be interconnected. Also, the strut widthcan vary as described with respect to the filters disclosed in the '429application.

After convergence of strut portions 14 a, 14 b at joining region 14 d,it transitions into elongated mounting strut portions 14 c which formflared mounting or anchoring region 17. The length of the strut portions14 c in the anchoring region 19 can vary, with increased/decreasedlength increasing the flexibility/rigidity of the struts. The thicknessof the strut portions can also vary to affect flexibility/rigidity.

As in the other embodiments described in the '429 applications, termssuch as interconnected, joined, etc., are used for ease of description,it being understood that preferably these portions are integral as theyare preferably formed from a single tube. Also, mounting struts andfilter struts used to describe the various embodiments disclosed hereincan be considered as mounting strut “portions” or “sections” and filterstrut “portions” or “sections” of the same struts if the filter isformed integrally, e.g. from a cut tube.

The tubular portion 18 is preferably in the form of a retrieval hook 92as described with respect to the embodiment of FIG. 20 in the '429application. Other retrieval structure can also be utilized. Hook 92 isdescribed in more detail below.

Two spiral cuts 45 a, 45 b are formed in the tube during manufacture,preferably by laser cutting, to enable two strips to be formed creatingfirst and second spacers 40 a, 40 b for the filter. In the collapsedposition, spacers 40 a, 40 b are in a substantially aligned positionwith respect to tubular portion 18, i.e. substantially flush with thetubular portion 18. Spacers 40 a, 40 b are maintained in this collapsedposition during delivery to the surgical site (see e.g. FIG. 1). Thespacers 40 a, 40 b have a shape memorized position forming loops asshown in FIG. 4A. Thus, once exposed from the delivery sheath, thespacers 40 a, 40 b move from their collapsed position to their shapememory looped position of FIGS. 4A, 4B and 5. The surface 42 a, 42 b ofthe loop of each spacer 40 a, 40 b engages opposite sides (lyingapproximately 180° apart) of the vessel wall to maintain centering ofthe cranial end of the filter and to space tubular portion 18 andretrieval hook 92 away from the vessel wall. This spacing preventstissue ingrowth around the hook, thereby making it easier to grasp andremove filter 10.

The loops of spacers 40 a, 40 b are open, somewhat oval shaped loops,terminate in ends 44 a, 44 b and lie in substantially alternate spiralplanes. The first strip cut into tubular portion 18 unravels from aproximal end 48 a of cutout 45 a to a distal end 46 a of cutout 45 a toform spiral spacer 40 a (see e.g. FIGS. 4B and 7). The second strip cutinto tubular portion 18 unravels from a proximal end 48 b of cutout 45 bto a distal end 46 b of cutout 45 b to form spiral spacer 40 b. In theFIG. 4 embodiment, the spacer loops 40 a, 40 b lie in planes that aresubstantially perpendicular to the longitudinal axis L of the tubularportion 18 and filter 10. However, alternatively the spacer loops couldlie in planes at angles other than 90 degrees and could lie in planesnot parallel to each other. Examples of different angles of spacer loopswith respect to the longitudinal axis of the tubular portion of thefilter are shown by way of example in FIG. 16. Two angled spacer loops(e.g. about 75 degrees) are designated by reference numeral 70′ andsmaller acute angled spacer loops, (e.g. about 45 degrees) aredesignated in phantom by reference numeral loop 70″. The othercomponents of the filter are identical to filter 10 and are designatedwith corresponding prime (′) reference numerals.

A comparison of FIGS. 8-10 illustrates that in the preferred embodiment,the length of tubular portion 18 remains substantially unchanged oncethe filter is implanted, even with the addition of the spacers. FIG. 8illustrates a cranial end of a filter of the '429 application showingthe retrieval hook H of the filter. The tubular portion P has a lengthL1 preferably ranging from about 0.100 inches to about 0.600 inches, andpreferably about 0.300 inches. The tubular portion 18 of FIG. 9, whichis the embodiment of FIG. 1, has a length L2, preferably ranging fromabout 0.500 inches to about 1.700 inches, and preferably about 0.881inches which is greater than length L1 due to the space needed to createthe spiral spacers 40 a, 40 b. However, once the spacers 40 a, 40 b movefrom their aligned position to their expanded position, the end of thetubular portion 18 contracts to close the gap created by the spiralcutouts to move to a length L3 which is preferably closed to length L1.

FIGS. 11 and 12 illustrate an alternate embodiment of the filter,designated by reference numeral 110. Filter 110 is identical to filter10, except for the tubular portion and spacer, and therefore has beenlabeled with numerals in the “100” series corresponding to the doubledigit numbering of filter 10. Thus, filter 110 has struts 114,interconnecting struts 114 a, 114 b, hooks 172 a, 172 b, etc. andtherefore for brevity these parts will not again be described.

Tubular portion 150 of filter 110 has a hook 192 identical to hook 92 ofFIG. 1. However, tubular portion 150 has a single spiral cutout 152,preferably formed by laser cutting, which forms a spiral spacer 154. Thespiral spacer 154 has a shape memory position of that shown in FIGS. 11and 12, extending radially from the tubular portion 150. When exposedfrom the sheath it unravels to move from a collapsed positionsubstantially flush with the tubular portion 150 to its shape memoryposition forming an open loop starting at end 155 and wrapping over 360degrees, terminating at edge 157. In this manner loop portions 156 and158 are 180 degrees apart and the circular loop surfaces contact theinner wall of the vessel. It is also contemplated that the spacer canwrap a smaller or greater distance (degrees) than that shown and be ovalor shapes other than circular. The loop can lie in a single plane or inmultiple planes.

FIG. 17 discloses an alternate embodiment of the filter which isidentical to the filter shown in FIG. 11 except for the spiral spacer264. The filter 210 is labeled with reference numerals in the “200series” corresponding to the “100 series” labeled parts of the FIG. 11embodiment and therefore has struts 214, hooks 272 a, 272 b, etc. Thetubular portion and spacer, being different, have non-correlatingreference numerals. More specifically, tubular portion 260 has a spiralcutout 262 to form a spacer 264. The distal (cranial) terminal end 266of the cutout 262 has an increased width to form a spacer end 269 ofincreased width “w”, shown in FIG. 17A. This provides increased supportfor the spacer as it reduces stress at that part. Spiral spacer 264loops around tubular portion 260 in a similar manner as spacer 154 ofFIG. 11, preferably wrapping over 360 degrees, although other degreesare contemplated. Opposed looped ends 267 and 269 are about 180° apartand the outer surfaces contact opposing sides of the vessel wall. Aswith spacers 254, the outer surfaces along the loop contact the vesselwall due to the circular configuration of the spacer 264.

In the embodiment of FIG. 18, the spacer 364 of filter 310 wraps aroundthe tubular portion 360 in different planes, as opposed to the singleplane of the embodiment of FIGS. 11 and 17. More specifically, in theexpanded position, spacer 364 emerges from the distal (cranial) end 366of cutout 365 and wraps at an angle toward the caudal end of the filter.Thus, as seen, the first end 372 of loop portion 370 lies in a planeproximal of the plane containing end 371 of loop portion 370 and distalof the plane containing the end 374 of loop portion 376. In other words,loop portion 378 lies, as viewed axially, between loops 370, 376. Theremaining portions of the filter are identical to filter 210 of FIG. 17and are labeled with corresponding parts in the “300” series.

FIGS. 19 and 19A illustrate the cranial end of an alternate embodimentof the filter having two looped spacers extending radially from thetubular portion 324. In the collapsed position of FIG. 19A, spacers 320,322 are wrapped around tubular portion 324 so they are substantiallyflush with the wall of the tubular portion 324. The spacers 320, 322 areformed by two spiral cutouts 326, 328 formed in the wall of tubularportion 324. In the expanded position, spacer 320 emerges from theproximal (caudal) end 329 of cutout 328, extending in a substantiallycircular or spiral path around the tubular portion 324, preferably forabout 300 degrees (although other degrees are contemplated), withsurfaces 321, 323 about 180° apart contacting opposing surfaces of thevessel wall. Spacer loop 320 terminates at end 323 to form an open loop.Spacer 322 emerges from the distal (cranial) end of the cutout 326,wrapping around tubular portion 324 in the direction opposite of spacer320. Similar to spacer 320, spacer 322 extends for about 300 degrees(although other degrees are contemplated), with opposing surfaces 325,327 contacting opposite portions of the vessel wall. Spacer loop 322terminates at end 331 to form an open loop. Hook 330 is preferablyidentical to hook 92 of the filter embodiment of FIG. 1.

In the embodiment of FIG. 20, open spacer loops 420 and 422 each startat a proximal end of cutout 426, with spacer 420 starting proximal ofspacer 422. Cutout 426 has first cutout 426 a and second cutout 426 b,formed in an alternating pattern. Spacers 420, 422 lie in multipleplanes, preferably wrap around tubular portion 424 in oppositedirections, extending for about 300 degrees (although other degrees arecontemplated) and have respective opposing surfaces 421, 423 and 425,427, respectively for contacting opposing sides of the vessel wall.Spacers 420, 422 terminate in ends 430, 432.

In the embodiment of FIG. 21, open spacer loops 520, 522 are formedemerging from the distal end of cutouts 526 a, 526 b of region 526, withspacer 520 emerging distal of spacer 522. Spacers 520, 522 lie indifferent planes. Similar to loops 420, 422 of the embodiment of FIG.21, spacer 520 has opposing surfaces 521 and 523 and spacer 522 hasopposing surfaces 525, 527. Loops 520, 522 lie in multiple planes.

In the embodiment of FIG. 22, open spacer loops 620, 622 extend from thedistal end of cutout 626 a, 626 b. As shown, the cutouts are formed inan intertwined spiral fashion resulting in a spiral spacer whenunraveled (expanded). The solid strip between cutout 626 a is designatedby reference numeral 630 and the solid strip between cutout 626 b isdesignated by reference numeral 632.

To enable movement between an expanded and collapsed configuration, thefilter of the embodiments described herein, as noted above, ispreferably made of shape memory metal material, such as Nitinol, anickel titanium alloy, and preferably manufactured from a laser cuttube. To facilitate passage of the filter through the lumen of thedelivery sheath 700 (shown in FIG. 13 in conjunction with the method ofinsertion) and into the vessel, cold saline is injected into thedelivery sheath or catheter 700 and around the filter in its collapsedposition within the delivery sheath 700. This shape memory materialcharacteristically exhibits rigidity in the austenitic state and moreflexibility in the martensitic state. The cold saline maintains thetemperature dependent filter in a relatively softer condition as it isin the martensitic state within the sheath. This facilitates the exit offilter from the sheath 700 as frictional contact between the filter andthe inner surface of the sheath would otherwise occur if the filter wasmaintained in a rigid, i.e. austenitic, condition.

Once ejected from the delivery sheath or catheter 700, the filter is nolonger cooled and is exposed to the warmer body temperature, whichcauses the filter to return towards its austenitic memorizedconfiguration.

In the placement (expanded) configuration, the filter moves towards itsmemorized position and the extent it returns to its fully memorizedposition will be dependent on the size of the vessel in which the filteris inserted. (The larger the vessel, the closer the filter comes toreturning to it's fully memorized position). The extent of movement ofthe spacer(s) to its fully memorized position could also be limited bythe size of the vessel.

The filter can be inserted through the jugular vein in the neck of thepatient or through the femoral vein in the leg of the patient or thearm. The filters can also be placed in the superior vena cava.

FIGS. 13-15 illustrate delivery and placement of the filter 10, by wayof example, in the inferior vena cava. Delivery catheter or sheath 700is inserted through the femoral vein “f” and advanced through the iliacarteries into the inferior vena cava. Delivery catheter 700 is withdrawnonce the tip of the sheath is adjacent the structure so that withdrawalof the sheath would place the filter in the desired location of FIG. 15.Tubing 704 and valve assembly 706 enable saline injection. Deliverycatheter 700 is withdrawn to enable filter 10 to be warmed by bodytemperature to transition to the expanded placement configuration. Theother filters described herein could be inserted in the same manner.Note it is implanted in the orientation such that filter section 19 isdownstream of the flared section 17. This enables blood clots or otherparticles to be directed to the center of the filter section by theangled struts. Thus the direction of insertion, e.g. upstream ordownstream direction, will determine how the filter is to be positionedin the delivery catheter.

The foregoing filters can be removed from access through the internaljugular or femoral vein. Various methods can be used to remove thefilter such as those described in commonly assigned co-pending '429application, the entire contents of which is incorporated herein byreference, including for example, slotted hooks, graspers, etc.

A recess or cutout is preferably provided at the tubular end portion toform a hook portion 90, as shown for example in FIGS. 7 and 9, having acurved hook 92 at the proximalmost end to receive a snare or otherdevice for removal as described in the filter of the '429 application.

This hook 92 is configured to receive a retrieval snare or otherretrieval device. A portion of the wall of the hook 90 is cut out toexpose the annular interior surface 94. This annular interior surface 94extends from radiused region 95 to distalmost edge 96. The interiorsurface 94, for ease of explanation, can be considered to have aninterior surface at the radiused region 95 and an interior surface 94 bat the hook 92. The interior surface 94 b accommodates a portion of atubular snare sheath. That is, the outer wall of the snare sheath (tube)can partially fit within the cut out region. This enhances removal asthe snare pulls the filter hook into collinear arrangement with thesheath tube as described and shown in FIGS. 13H-13N of the '429application. The radiused region 95, spaced axially (proximal) from thehook 92, includes a radiused or curved edge defined by radiused sidewalls 97 a, 97 c and top wall 97 b. The angled side walls 97 a, 97 cform camming surfaces to direct the hook 90 and filter into theretrieval sheath.

When the filter is grasped by the retrieval device and pulled distallyto disengage from the vessel walls, the spacers flex inwardly. This isshown for example in FIG. 15, wherein spacers 40 a, 40 b of filter 10flex in the direction of the arrow as the filter is pulled intoretrieval sheath 800.

It should be appreciated, that the hook can be formed in other ways toprovide an interior annular surface to function in a similar manner assurface 94, i.e. to receive the snare tube. When the filter is pulledinto the retrieval sheath it is collapsed for removal.

FIG. 9A illustrates an alternate embodiment of the hook portion 600having an elongated hook 602 curving inwardly. This provides increasedhooking area for the retrieval snare.

To facilitate removal of the filter from the vessel, cold saline can beinjected onto the implanted filter to change the temperature of thefilter to move it to a relatively softer condition to facilitate thefilter being drawn into the retrieval sheath. That is, injection of coldsaline will cause the filter to approach its martensitic state, bringingthe filter to a more flexible condition. The flexible conditionfacilitates the collapse and withdrawal of the filter into the retrievalsheath by decreasing the frictional contact between the filter and theinner surface of the retrieval sheath.

A delivery system which can be used for the filter of the presentinvention which includes a filter cartridge, is shown and described inthe '429 application.

While the above description contains many specifics, those specificsshould not be construed as limitations on the scope of the disclosure,but merely as exemplifications of preferred embodiments thereof. Forexample, the foregoing filters can be inserted in other regions of thebody. Also, the foregoing filters can be made of materials other thanshape memory material. Those skilled in the art will envision many otherpossible variations that are within the scope and spirit of thedisclosure as defined by the claims appended hereto.

What is claimed is:
 1. A vascular device comprising a first distalregion and a second proximal region, the device movable between acollapsed position for delivery to a vessel and an expanded position forplacement within the vessel, the second region having a mountingportion, the second region including a vessel engaging portion at asecond end portion, the first region having a first spacer positioned ata distal portion and movable from a substantially flush collapsedposition to an expanded position, the first spacer unwinding as it movesfrom the collapsed position to the expanded position to extend radiallywith respect to a longitudinal axis of the device such that it extendsradially outwardly from an outer surface of the device and is spacedradially from the outer surface as it loops around the outer surface,wherein the first distal region includes a tubular region having a firstcutout and the first spacer is formed from the first cutout.
 2. Thedevice of claim 1, wherein the first spacer is formed of shape memorymaterial forming a loop in a shape memorized position.
 3. The device ofclaim 1, wherein the first spacer forms first and second loops, eachloop extending on opposing sides of the longitudinal axis of the device.4. The device of claim 1, wherein movement of the first spacer to theexpanded position contracts the tubular region to close a gap created bythe first cutout.
 5. The device of claim 1, wherein the first spacer hasa looped expanded position and during delivery in the collapsed positionit is substantially flush with a tubular region of the first distalregion.
 6. The device of claim 1, wherein a distal region of the firstcutout has an increased width so the first spacer has an increased widthregion.
 7. The device of claim 1, wherein the first spacer wraps over360 degrees around the tubular region.
 8. A vascular device comprising afirst distal region and a second proximal region, the device movablebetween a collapsed position for delivery to a vessel and an expandedposition for placement within the vessel, the second region having amounting portion, the second region including a vessel engaging portionat a second end portion, the first region having a first spacerpositioned at a distal portion and movable from a substantially flushcollapsed position to an expanded position, the first spacer unwindingas it moves from the collapsed position to the expanded position toextend radially with respect to a longitudinal axis of the device suchthat it extends radially outwardly from an outer surface of the deviceand is spaced radially from the outer surface as it loops around theouter surface, and further comprising a second spacer axially spacedfrom the first spacer, the second spacer movable from a substantiallyflush collapsed position to an expanded position to extend radially withrespect to the longitudinal axis of the device.
 9. The device of claim8, wherein the first distal region includes a tubular region and a firstcutout and a second cutout, the first spacer unraveling from the firstcutout and the second spacer unraveling from the second cutout.
 10. Thedevice of claim 9, wherein the first spacer unravels from a proximal endof the first cutout to a distal end of the first cutout and the secondspacer unravels from a proximal end of the second cutout to a distal endof the second cutout.
 11. The device of claim 8, wherein the device isformed from a laser cut tube and composed of shape memory material. 12.The device of claim 8, wherein the first distal region includes atubular region and the first and second spacers wrap around the tubularregion in opposite directions.
 13. The device of claim 8, wherein thefirst and second spacers are intertwined.
 14. A vascular devicecomprising a body including a single tube, the tube cut to create aplurality of elongated struts, a tubular region distal of the struts andhaving a first cutout formed therein to form a first spacer and a secondcutout formed therein to form a second spacer axially spaced from thefirst spacer, the first and second spacers substantially aligned withthe tubular region in a collapsed position and extending radiallyoutwardly from the tubular region in an expanded position, wherein thefirst and second spacers are formed from spiral cutouts in the tubularregion.
 15. The device of claim 14, wherein the device has a firstlength from a proximalmost end to a distalmost end in a collapsedposition and a second length from the proximalmost end to the distalmostend in an expanded position, the first length being greater than thesecond length.
 16. A vascular device comprising a body including asingle tube, the tube cut to create a plurality of elongated struts, atubular region distal of the struts and having a first cutout formedtherein to form a first spacer and a second cutout formed therein toform a second spacer axially spaced from the first spacer, the first andsecond spacers substantially aligned with the tubular region in acollapsed position and extending radially outwardly from the tubularregion in an expanded position, wherein a portion of the tubular regioncontracts to close a gap created by the cutouts when the first andsecond spacers move to the expanded position.